Centrifugal air propellers



Aug. 25, 1959 E. G. STILL CENTRIFUGAL AIR PROPELLERS United States patgflt 2,901,047 CENTRIFUGAL AIR PROPELLERS Elmer Grant Still, Livermore, Calif. Application September 23, 1957, Serial No.'68 5,694

2 Glaims. (Cl. 170-135) V This'invention relatesto improvements in centrifugal air propellers in which longitudinal (axial) vanes secured to and radiating from a central shaft are rotated rapidly to create thrust-giving partial vacuum on a disc by virtue of centrifugal force throwing the air outward.

The objects of this invention are to increase the efficiency and safety of aircraft, so as to equal or surpass birds andbats in these respects; to enable aircraft to take off and land vertically and so as 'to hover as a still tlyer, and other objects hereinafter mentioned.

In the accompanying drawing, Fig. 1 is a view in central vertical section of the device, and Fig. 2 is a plan view of the'propeller itself, looking downward'from the line 2-2 of Fig. 1.

This application is a continuation-in-part of application Serial No. 459,805, filed October I, 1954, and ofapplication Serial No. 480,048, filed January 5, 1955, both for centrifugal air propellers. r t

In the preferred form and when arranged for Vertical lift, this device comprises a central vertical shaft 2 of suitable size and preferably made of steel; a bearing 8 at each end of the shaft, securely set in an arm or framework 9; flat longitudinal vanes 3, preferably of sheet metal or plastic, secured to the shaft and radiating symmetrically-that is, in balanced relationshipfrorn the shaft and preferably several times as long axially as their radial width; a disc 4, also of sheet metal or plastic or the like, secured at an angle of ninety degrees to the upper ends of said vanes, with small holes (perforations) 7 through said disc, preferably dispersed symmetrically, for admitting air from outside into the propeller during rotation to prevent the formation of a thrust-annulling partial vacuum on the inward side of said disc, and/or with adjacent portions of the vanes being cut away, forming a notch, or slot, in each of said vanes, so as to also cause outside air to enter the propeller during rotation for the same purpose, entering at an angle of ninety degrees to the shaftcentripetally-directly against the action of the vanes in throwing the air outward by centrifugal force, which also acts at right angles to the shaft, but is lessened in eifect at that point by said portions of the vanes being cut away; a frusturn 6 of a cone or other central symmetrical block surrounding the shaft (a cylindrical hole being provided through the center of the frustum or the like for fitting onto the shaft), for the purpose of filling in the corner formed by the vanes at an angle of ninety degrees to the shaft with said disc and the shaft, a thrust-annulling partial vacuum being most likely to form in this corner between the vanes during rotation of the propeller; a second disc 4A secured to the lower ends of said vanes and extending at least as far outward as the outer ends of said vanes and preferably considerably further, with similar perforations through this second disc; an annular flange 15 secured to the rim of this disc or near the rim thereof, for the purpose of preventing air from entering around this corner into the partial vacuum that forms on the upper side of this disc during rotation; a third disc, of the 2,901,047 Patented Aug. 25, 1959 nected by'mean's of the bevel gears 11 and 12 and the gears 13 and 14 to the shaft. However, some of these elements may be omitted, resulting simply in a less efficient yet workable form of the device.

The vanes 3A throw out air by centrifugal force as do the vanes 3 and thus create a partial vacuum of high degree between said discs 4A and 4B, sucking air down through the perforations 7 and hence heightening the thrust giving partial vacuum that forms on the upper surface of disc 4A; and on account of the discs 4A and 4B being so near together, the partial vacuum that forms on their surfaces facing each other is equalized, and hence there is nothrust exerted either upwardly or downwardly on said surfaces; all of this occurring during rotation. This arrangement constitutes a distinct improvement over similar devices, since the thrust-giving partial vacuum is formed in two ways atthe same time.

In order to accomplish the objects of the invention, it is necessary to maintain normal air pressure or as near to it is possible on the inward side of the uppermost disc, at the air-entering end of the device, during rotation, while at the same time creating and maintaining as high a degree of partial'vacuum as possible on the upper side of said second disc. p

T he present invention also diifers from previous devices of this kind in that the disc-like surface on which the thrust-giving partial vacuum is formed extends preferably considerably further radially outward at an angle of ninety degrees than the outer ends of the vanes at and near the places where said surface and vanes meet, thus increasing considerably the area of surface on which such thrust is produced without increasing more than slightly the power expended at any given speed.

In some previous devices of this kind, the disc-shaped cover at the air-entering end of the propeller extended only about half-way as far outward as the ends of the vanes, thus permitting a great quantity of air to rush axially into the propeller and having to be thrown out again, all to no purpose and at great waste of power, besides tending to destroy the thrust-yielding partial vacuum at the other end of the propeller, while at the same time creating a thrust-annulling partial vacuum on the inward side of this short cover. Likewise, in the propeller of my patent numbered 2,531,748, and dated Nov. 28, 1950, too much air is permitted to rush in, due to the air entering under the flaring cover al at an angle between axial and centripetal.

When the perforations 7 in the uppermost disc are used, it is not really necessary to have the notches 5 nor the central frustrum 6, except that in wet weather when the device is located outside the nacelle these perforations may become clogged with water and hence useless. However, this propeller disturbs the surrounding air so little that it may always be used within the nacelle of the aircraft.

The best relative size of the various parts of the propeller can only be determinedas to efliciency-by trial-anderror experimentation. However, the greater the axial length of vanes 3 as compared with their radial width, thetrial and error can determine the best diameter, number and distribution for the perforations.

All of the revolving parts of the propeller would be arranged symmetrically in relation to the axis of the central shaft 4; that is, all such parts would be counterbalanced by diametrically opposite parts similar in shape, size, weight and distance from this axis, so as to prevent vibration during rotation, -or by equivalent construction; that is, in balanced relationship to the central shaft.

If five percent of a full vacuum were created on said second disc and none under theupper cover, the resulting lift from a five-foot disc cover would be 5 percent of 14.7 pounds (air pressure per square inch) times 144 (square inches in a square foot) times 19.63 (square feet in a 5-foot disc), or over 2,077 pounds lift. A 7-foot circular cover would yield nearly twice this lift or thrust. Since man can use many mechanical devices that a bird or bat cannot and also use stronger materials and even higher speed, he should be able to attain even greater efiiciency in flight than birds or bats; and we know that many birds lift at the rate of 100 to 200 pounds per horsepower available in their wing muscles, while modern airplanes lift only about 20 pounds per horse-power used and helicopters still less-about 12 to 15. Hence, if a nine-pound wild goose were no more efiicient than an airplane, it would need to have nearly half a horse-power in its wing muscles; but experiments by scientists show that it is able to exert only about one-thirtieth of a horse-power. Since centrifugal force increases directly with the speed of revolution (when the wieght of the revolving particles and their distance from center remain the same, centrifugal propellers should be as efficient at high as at low speed; while with screw propellers each doubling of the speed produces only about 50 percent more thrust or lift.

This propeller device may be used instead of screw propellers or others on an airplane (preferably one with narrow wing spread) or instead of those now used on a helicopters, and also for propelling ice boats and other boats or even ships, motor cars, railroad cars, etc. In a flying .machine these devices for propelling, lifting or steering, or even those for balancing, could be enclosed within the nacelle or other stream-lined enclosures, since they may use the same air over and over and do not much disturb the surrounding air; and when so enclosed much head resistance and air friction during rapid flight are thus averted. When used for forward propulsion, this propeller would, of course, be arranged with its central shaft 2 horizontal instead of vertical.

I claim: 7

1. In a propulsion mechanism, a rotary driven shaft; a plurality of vanes secured to the shaft, extending axially coextensively and radiating in balanced relationship from the shaft; a disc centrally secured to one end of said vanes at an angle of ninety degrees to the shaft and extending as far outward as the nearby outer ends of said vanes; a second disc centrally disposed a comparatively short distance from said first-mentioned disc, at an angle of ninety degrees to the shaft and extending as far outward as the nearby outer ends of said vanes, but on the opposite side of said first-mentioned disc from said vanes, and a second set of such radiating vanes extending completely between said two discs and of the same radial length as said discs; said first-mentioned disc being provided with perforations.

2. A propulsion mechanism as in claim 1, said second set of radiating vanes being considerably longer radially than axially. I 7

References Cited, in the file of this patent UNITED STATES PATENTS 

